1、Designation: D 1631 99 (Reapproved 2004)Standard Test Method forWater in Phenol and Related Materials by the IodineReagent Method1This standard is issued under the fixed designation D 1631; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method
3、covers the determination of water inphenol and related materials such as cresols, xylenols, naph-thalene, pyridine, and quinoline.1.2 This test method has been found applicable to a varietyof materials varying in water content from 100 mg/kg tosolutions containing a relatively high percent of water.
4、1.3 The following applies to all specified limits in thisstandard: for purposes of determining conformance with thisstandard, an observed value or a calculated value shall berounded off “to the nearest unit” in the last right-hand digitused in expressing the specification limit in accordance withthe
5、 rounding-off method of Practice E29.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory lim
6、itations prior to use. For specific hazardstatements, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D 1364 Test Method for Water in Volatile Solvents (KarlFischer Reagent Titration Method)D 3437 Practice for Sampling and Handling Liquid CyclicProductsD 3852 Practice for Sampling and Handl
7、ing Phenol,Cresols, and Cresylic AcidD 4790 Terminology of Aromatic Hydrocarbons and Re-lated ChemicalsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 Other Document:3OSHA Regulations,29CFR, Paragraphs 1910.1000 and1910.12003. Terminology3.1 See
8、Terminology D 4790 for definition of terms used inthis test method.4. Summary of Test Method4.1 When solutions of iodine in methanol and of sulfurdioxide in pyridine are mixed in the presence of water, thefollowing reaction occurs:I21 SO21 H2O2HI 1 SO3(1)4.1.1 Sufficient pyridine is present in the r
9、eagent to consumethe hydriodic acid and sulfur trioxide:4.1.2 The pyridine sulfur trioxide salt reacts with the metha-nol, this preventing a second mole of water from beingconsumed:4.2 When the pyridine solution contains water and the sulfurdioxide is titrated with iodine in methanol solution, thepl
10、atinum electrodes remain polarized until all the water reacts.1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.02 on Oxygenated Aromatics.Current edition approved Aug. 1, 2004. Publishe
11、d August 2004. Originallyapproved in 1959. Last previous edition approved in 1999 as D 1631 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Documen
12、t Summary page onthe ASTM website.3Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.A slight exces
13、s of iodine depolarizes the electrodes, allowingcurrent to flow through the microammeter which indicates theend point.5. Significance and Use5.1 This test method is particularly useful for determiningsmall amounts of water in hygroscopic materials. This testmethod is suitable for setting specificati
14、ons on materialsreferenced in the scope. It may also be used as an internalquality control tool and in development or research work.6. Interferences6.1 This test method is not applicable in the presence ofmercaptans, peroxides, or appreciable quantities of aldehydesor amines.6.2 If ketones are prese
15、nt in the sample, interference fromthem can be avoided by employing the glycol-pyridine samplesolvent specified in Test Method D 1364.7. Apparatus7.1 The apparatus shall be assembled as shown in Fig. 1.Any suitable modification permitting equal facility and accu-racy may be used. Automatic titration
16、 equipment is commer-cially available and may be used.8. Reagents8.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchs
17、pecifications are available.4Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Iodine SolutionDissolve 150 g of iodine (I2) crystalsin 3 L of anhydrous methanol. Place th
18、e solution in the reagentbottle connected to the buret as shown in Fig. 1.8.3 Methanol, anhydrous, containing less than 0.05 % wa-ter.8.4 Pyridine SolutionPlace 4000 mL of refined gradepyridine in a 5000-mL distilling flask. Distill over and discard400 mL of forecut at atmospheric pressure. Distill
19、off 3400 mLof center cut and transfer to a suitable glass bottle fitted with atwo-hole stopper. Through one hole of the stopper insert apiece of glass tubing that extends almost to the bottom of thebottle; through the other hole insert a short piece of glasstubing to serve as a vent. Through the lon
20、g tube add 400 g ofrefrigerant-grade sulfur dioxide (SO2) dried through concen-trated sulfuric acid (H2SO4sp gr 1.84), and allow the solutionto cool. Fit the vent tube with a drying tube and an aspiratorbulb; connect the long tube with an adapter suitable forintroducing the reagent into the titratio
21、n flask. For conveniencein measuring, a suitable reservoir may be placed in the system.NOTE 1In place of the divided reagents described in 8.2, 8.3, and 8.4it is permissible to employ the single solution reagent specified in TestMethod D 1364 or commercial Karl Fischer reagents. Pyridine-freereagent
22、s are available from various laboratory suppliers and may be usedif suitable for the material being tested.8.5 When handling Karl Fischer reagent refer to PracticeD 3437.9. Hazards9.1 Consult current OSHA regulations suppliers MaterialSafety Data Sheets and local regulations for all materials usedin
23、 this test method.9.2 Phenol, pyridine, and related materials are extremelytoxic when ingested and corrosive to the skin. Appropriateprecaution must be exercised when handling them.10. Sampling10.1 Sample in accordance with Practice D 3852 for propersampling and handling of phenol and related materi
24、als ana-lyzed by this test method (see 9.1 and 9.2.).10.2 Precautions must be taken in sampling to preclude anypossibility of contamination with atmospheric moisture adher-ing to the walls of the pipet.10.3 The sample size recommended, on the basis of watercontent expected is as follows:Expected Wat
25、er Content, % Size of Specimen, g0.01 to 0.03 500.03 to 0.3 250.3to0.6 104Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryC
26、hemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Titration AssemblyD 1631 99 (2004)20.6to1.0 51.0to5.0 25.0 to 10.0 110.0 to 20.0 0.511. Standardization of Sulfur DioxideIodine Reagent11
27、.1 By means of pressure from the aspirator bulb, transfersufficient pyridine solution (Warningsee 9.2) to the titrationflask to cover the electrodes. If an automatic titration apparatusis used, a small amount of methanol may be added to thepyridine to improve the response of the titrator. Turn on th
28、emagnetic stirrer and turn the “zero-set” knob until a reading of70 A is obtained on the ammeter. Add the iodine solutiondropwise from the buret until the ammeter reads a maximumvalue, about 130 A. Remove the drying tube from the sidearmand quickly introduce an amount of distilled water, or water of
29、equivalent purity, at least equal to that to be determined,weighed to the nearest 0.1 mg by means of a suitable weighingpipet. Immediately replace the drying tube.11.2 Titrate with the iodine solution, approaching the endpoint dropwise until the maximum value, about 130 A, isobtained on the ammeter.
30、 The standardization should berepeated daily. If desired, a suitable accurately weighed amountof sodium tartrate dihydrate reagent may be used in place ofwater as follows: Accurately weigh a small aluminum weigh-ing dish containing about 0.20 to 0.22 g of powdered sodiumtartrate dihydrate (Na2C4H4O6
31、2H2O) to the nearest 0.1 mg.Remove the stopper from the titration flask and introduce thetartrate by inserting the spout into the opening and gentlytapping so that the powder falls freely into the liquid withoutcontacting the side walls. Do not brush out the dish: accuratelyreweigh it and calculate
32、the weight of tartrate used bydifference. Quickly reseal the flask, turn on the stirrer, andtitrate to the end point. Record the volume of reagent andweight of tartrate used.11.3 Calculate the water equivalent of the sulfur dioxide-iodine reagent as follows:F 5 100A/B (2)where:F = water equivalent o
33、f the reagent, g/100 mL,A = water added, g, andB = volume of reagent used for the titration, mL.If sodium tartrate dihydrate is used in place of water forstandardizing:F 5 15.66S/B (3)where S = tartrate used, g.12. Procedure12.1 Repeat the procedure described in Section 11 adding,instead of water, a
34、n amount of specimen selected according toSection 10. Record all weighings to the nearest 0.1 mg.As longas an excess of pyridine remains in the titration flask, furtheradditions of specimen and titration may be made. (WarningSee 9.2.)NOTE 2The titration flask may be removed and cleaned betweenspecim
35、ens. Washing should be followed by an alcohol or acetone rinse anddrying in a ventilated oven at 100 to 130C for several hours. The cleanflask may be cooled in a desiccator or attached to the buret to cool withthe openings closed with drying tubes. If a series of specimens is to betested, it is pref
36、erable to continue additions of specimens and titration (andaddition of pyridine if necessary) until the volume of liquid in the flask istoo great for further titration.NOTE 3Visual observation of the end point may be used in place ofthe more precise electrometric method described if the solution is
37、 verylightcolored. During the titration the solution turns yellow after theaddition of the first few millilitres of the reagent. This color change mustnot be confused with the true end point, which is brown. The transitionfrom yellow to brown is quite sharp and easily reproducible.13. Calculation13.
38、1 Calculate the amount of water in the specimen asfollows:Water, weight % 5 CF/D (4)where:C = sulfur dioxide-iodine reagent required for titration ofthe specimen, mL, andD = weight of specimen used, g.14. Precision and Bias14.1 Intermediate Precision (formerly calledRepeatability)Duplicate results s
39、hould be considered suspectif they differ by more than the following:Range, %Intermediate Precision(By Same Operator)Reproducibility(By Two Different Laboratories)0.01 to 0.12 0.0035 0.02114.1.1 Data on which these precision values are based aregiven in the 1959 Report of Committee D16, Proceedings,
40、ASTM, Vol 59, 1959.14.2 BiasSince there is no accepted reference materialsuitable for determining the bias in this test method, bias hasnot been determined.15. Keywords15.1 cresols; iodine; Karl Fischer method; naphthalene;phenol; pyridine; quinoline; water; xylenolsD 1631 99 (2004)3ASTM Internation
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42、own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be
43、addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards,
44、 at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 1631 99 (2004)4
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